Christians, Hauke (2022)
Mesoporous and Crystalline Carbonaceous Materials.
Technische Universität Darmstadt
doi: 10.26083/tuprints-00020330
Dissertation, Erstveröffentlichung, Verlagsversion
Kurzbeschreibung (Abstract)
Due to their unique property combinations, carbonaceous materials are used in a variety of applications, ranging from high temperature resistant graphites with high electrical conductivity as electrodes to gas tight materials in as bearing rings in applications with high mechanical stress to highly porous adsorption materials. Carbonaceous materials with both mesoporous structures and high temperature stability are becoming more important for applications such as electrochemical applications, adsorption of huge molecules, and other specialty applications. This combination of properties cannot be achieved with “classical” carbonaceous materials, thus current research is focusing on development of such materials.
In this work, two possible methods to obtain these materials are examined, focusing on tuning the properties of obtained carbonaceous materials via the synthesis parameters. Via annealing of commercial activated carbons (highly microporous and amorphous) in a temperature range between 1000 and 1900 °C, carbonaceous materials with drastically increased thermooxidative stability and much larger pores could be obtained. It could be shown how changes in annealing temperature and choice of precursor material could influence pore structure and carbon microstructure to a certain degree.
Furthermore, carbide-derived carbons (CDC) obtained from chlorination of metal carbides at elevated temperatures were examined. It could be shown, that all binary carbides with sodium chloride type crystallite structure were able to yield highly crystalline carbonaceous materials with meso and macropores. The temperature at which a transition from microporous and amorphous carbons to graphitic materials is observed directly correlates with the structure of the precursor material, i.e. their lattice constant. In addition, these CDCs were applied exemplary as support material for platinum catalysts for the oxygen reduction reaction. The properties of the CDCs highly influenced the quality of the catalyst layer on the working electrode, resulting in superimposed effects influencing the electrochemical tests. Therefore, optimization of the test methods is necessary in order to obtain accurate results and to make definite statements. Nevertheless, it could be shown that CDCs in general can be suitable model materials for examining the influence of the catalyst support material on catalyst properties and its activity.
Typ des Eintrags: | Dissertation | ||||
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Erschienen: | 2022 | ||||
Autor(en): | Christians, Hauke | ||||
Art des Eintrags: | Erstveröffentlichung | ||||
Titel: | Mesoporous and Crystalline Carbonaceous Materials | ||||
Sprache: | Englisch | ||||
Referenten: | Etzold, Prof. Dr. Bastian J. M. ; Kramm, Prof. Dr. Ulrike | ||||
Publikationsjahr: | 2022 | ||||
Ort: | Darmstadt | ||||
Kollation: | ix, 87 Seiten | ||||
Datum der mündlichen Prüfung: | 23 Mai 2022 | ||||
DOI: | 10.26083/tuprints-00020330 | ||||
URL / URN: | https://tuprints.ulb.tu-darmstadt.de/20330 | ||||
Kurzbeschreibung (Abstract): | Due to their unique property combinations, carbonaceous materials are used in a variety of applications, ranging from high temperature resistant graphites with high electrical conductivity as electrodes to gas tight materials in as bearing rings in applications with high mechanical stress to highly porous adsorption materials. Carbonaceous materials with both mesoporous structures and high temperature stability are becoming more important for applications such as electrochemical applications, adsorption of huge molecules, and other specialty applications. This combination of properties cannot be achieved with “classical” carbonaceous materials, thus current research is focusing on development of such materials. In this work, two possible methods to obtain these materials are examined, focusing on tuning the properties of obtained carbonaceous materials via the synthesis parameters. Via annealing of commercial activated carbons (highly microporous and amorphous) in a temperature range between 1000 and 1900 °C, carbonaceous materials with drastically increased thermooxidative stability and much larger pores could be obtained. It could be shown how changes in annealing temperature and choice of precursor material could influence pore structure and carbon microstructure to a certain degree. Furthermore, carbide-derived carbons (CDC) obtained from chlorination of metal carbides at elevated temperatures were examined. It could be shown, that all binary carbides with sodium chloride type crystallite structure were able to yield highly crystalline carbonaceous materials with meso and macropores. The temperature at which a transition from microporous and amorphous carbons to graphitic materials is observed directly correlates with the structure of the precursor material, i.e. their lattice constant. In addition, these CDCs were applied exemplary as support material for platinum catalysts for the oxygen reduction reaction. The properties of the CDCs highly influenced the quality of the catalyst layer on the working electrode, resulting in superimposed effects influencing the electrochemical tests. Therefore, optimization of the test methods is necessary in order to obtain accurate results and to make definite statements. Nevertheless, it could be shown that CDCs in general can be suitable model materials for examining the influence of the catalyst support material on catalyst properties and its activity. |
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Alternatives oder übersetztes Abstract: |
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Status: | Verlagsversion | ||||
URN: | urn:nbn:de:tuda-tuprints-203307 | ||||
Sachgruppe der Dewey Dezimalklassifikatin (DDC): | 500 Naturwissenschaften und Mathematik > 540 Chemie | ||||
Fachbereich(e)/-gebiet(e): | 07 Fachbereich Chemie 07 Fachbereich Chemie > Ernst-Berl-Institut > Fachgebiet Technische Chemie 07 Fachbereich Chemie > Ernst-Berl-Institut > Fachgebiet Technische Chemie > Technische Chemie I |
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Hinterlegungsdatum: | 03 Jun 2022 12:05 | ||||
Letzte Änderung: | 11 Nov 2022 09:37 | ||||
PPN: | 496555049 | ||||
Referenten: | Etzold, Prof. Dr. Bastian J. M. ; Kramm, Prof. Dr. Ulrike | ||||
Datum der mündlichen Prüfung / Verteidigung / mdl. Prüfung: | 23 Mai 2022 | ||||
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